v2.5.1: Admin theme refactor, Navigation plugin, user roles, guide restructure

- Reorganize admin into admin/theme/default/ (views + assets)
- Rename GuideNav to Navigation plugin (essential, protected)
- Plugin assets support (SCSS/CSS) loaded after theme CSS
- User roles: Admin, Content Manager, BI Manager, Site Admin
- Role-based access control (RBAC) for admin routes and sidebar
- Guide restructure: sub-topics in separate folders with sidebar nav
- Dynamic breadcrumb for homepage and subdirectories
- Fix theme path traversal (../../ -> ../) in admin.php
- Fix CodeMirror mode load order (xml -> css -> js -> htmlmixed -> php)
- Fix editor-toolbar.js null checks for plugin edit pages
- Layout select from theme.json with live frontmatter update
- Footer sticky at bottom of viewport (min-height: 100vh)
- Breadcrumb color fix (var(--nav-font) -> var(--header-bg))
- Remove language switcher from guide pages
- Update README.md and README.en.md
- Bump version to 2.5.1

admin/theme/default/assets/codemirror/mode/htmlmixed.min.js

@@ -0,0 +1 @@
+!function(t){"object"==typeof exports&&"object"==typeof module?t(require("../../lib/codemirror"),require("../xml/xml"),require("../javascript/javascript"),require("../css/css")):"function"==typeof define&&define.amd?define(["../../lib/codemirror","../xml/xml","../javascript/javascript","../css/css"],t):t(CodeMirror)}(function(m){"use strict";var l={script:[["lang",/(javascript|babel)/i,"javascript"],["type",/^(?:text|application)\/(?:x-)?(?:java|ecma)script$|^module$|^$/i,"javascript"],["type",/./,"text/plain"],[null,null,"javascript"]],style:[["lang",/^css$/i,"css"],["type",/^(text\/)?(x-)?(stylesheet|css)$/i,"css"],["type",/./,"text/plain"],[null,null,"css"]]};var a={};function d(t,e){e=t.match(a[t=e]||(a[t]=new RegExp("\\s+"+t+"\\s*=\\s*('|\")?([^'\"]+)('|\")?\\s*")));return e?/^\s*(.*?)\s*$/.exec(e[2])[1]:""}function g(t,e){return new RegExp((e?"^":"")+"</\\s*"+t+"\\s*>","i")}function o(t,e){for(var a in t)for(var n=e[a]||(e[a]=[]),l=t[a],o=l.length-1;0<=o;o--)n.unshift(l[o])}m.defineMode("htmlmixed",function(i,t){var c=m.getMode(i,{name:"xml",htmlMode:!0,multilineTagIndentFactor:t.multilineTagIndentFactor,multilineTagIndentPastTag:t.multilineTagIndentPastTag,allowMissingTagName:t.allowMissingTagName}),s={},e=t&&t.tags,a=t&&t.scriptTypes;if(o(l,s),e&&o(e,s),a)for(var n=a.length-1;0<=n;n--)s.script.unshift(["type",a[n].matches,a[n].mode]);function u(t,e){var a,o,r,n=c.token(t,e.htmlState),l=/\btag\b/.test(n);return l&&!/[<>\s\/]/.test(t.current())&&(a=e.htmlState.tagName&&e.htmlState.tagName.toLowerCase())&&s.hasOwnProperty(a)?e.inTag=a+" ":e.inTag&&l&&/>$/.test(t.current())?(a=/^([\S]+) (.*)/.exec(e.inTag),e.inTag=null,l=">"==t.current()&&function(t,e){for(var a=0;a<t.length;a++){var n=t[a];if(!n[0]||n[1].test(d(e,n[0])))return n[2]}}(s[a[1]],a[2]),l=m.getMode(i,l),o=g(a[1],!0),r=g(a[1],!1),e.token=function(t,e){return t.match(o,!1)?(e.token=u,e.localState=e.localMode=null):(a=t,n=r,t=e.localMode.token(t,e.localState),e=a.current(),-1<(l=e.search(n))?a.backUp(e.length-l):e.match(/<\/?$/)&&(a.backUp(e.length),a.match(n,!1)||a.match(e)),t);var a,n,l},e.localMode=l,e.localState=m.startState(l,c.indent(e.htmlState,"",""))):e.inTag&&(e.inTag+=t.current(),t.eol()&&(e.inTag+=" ")),n}return{startState:function(){return{token:u,inTag:null,localMode:null,localState:null,htmlState:m.startState(c)}},copyState:function(t){var e;return t.localState&&(e=m.copyState(t.localMode,t.localState)),{token:t.token,inTag:t.inTag,localMode:t.localMode,localState:e,htmlState:m.copyState(c,t.htmlState)}},token:function(t,e){return e.token(t,e)},indent:function(t,e,a){return!t.localMode||/^\s*<\//.test(e)?c.indent(t.htmlState,e,a):t.localMode.indent?t.localMode.indent(t.localState,e,a):m.Pass},innerMode:function(t){return{state:t.localState||t.htmlState,mode:t.localMode||c}}}},"xml","javascript","css"),m.defineMIME("text/html","htmlmixed")});